1. Field of the Invention
The present invention relates to driving method and system for driving an electrical rotating machine having two rotors, one of the two rotors being driven independently of the other rotor by means of a compound current.
2. Description of the Related Art
A Japanese Patent Application First Publication No. Heisei 11-356015 published on Dec. 24, 1999 exemplifies a previously proposed electrical rotating machine of a three-layer structure having two rotors and a single common stator. A compound (alternating) current which is a sum of sinusoidal waves is caused to flow through a coil of the stator of the previously proposed electrical rotating machine from an (two-level) inverter. An inverter to drive the respective rotors is assigned to be a multi-phase inverter. A neutral point of an armature coil (stator coil) is generally a single. Such an electrical rotating machine as described above can be used to a vehicle such as a hybrid vehicle.